<p>In the design of deep soft rock tunnels, full consideration should be paid to preventing lining damage caused by time-dependent deformation of the surrounding rock throughout the entire life cycle. The composite yielding support system (deformable primary lining–buffer layer–secondary lining) has great potential in effectively ensuring the safety of tunnels during both construction and operation. In this study, a theoretical modelling attempt is conducted to predict the life-cycle mechanical responses of tunnels employing a composite yielding support system. In the established model describing the interaction between the time-dependent surrounding rock and composite yielding support system, the deformation process of both the deformable primary lining and buffer layer exhibits three-stage characteristics. The mathematical derivation is carried out in the unsupported stage, the deformable primary lining-supported stage, and the composite yielding support system-supported stage, respectively. Among them, the latter two stages are further subdivided into three stages. Analytical solutions for displacements and interface contact stresses in each stage are provided. The proposed solutions in this study can be reduced to the two simple cases provided in previous references. In addition, a numerical simulation is conducted on a tunnel using a composite yielding support system, and the consistency between the numerical simulation results and theoretical prediction results is verified. Finally, a detailed parametric investigation is performed based on the proposed analytical solutions. The supporting effects of different types of support systems are compared; the influences of several major parameters on the life-cycle safety of tunnels are determined, including important parameters of the compressible element, buffer layer, and surrounding rock. Some practical suggestions on the design of composite yielding support system are provided.</p>